When I first sat in the House of Commons gallery as a reporter (in 1985 – appallingly long ago) I wondered, looking down, who among the hundreds of faces below might become the big figures. As it turned out, there were three future Prime Ministers below: John Major, Tony Blair, and Gordon Brown. David Cameron was still at school. I won’t claim to have spotted any of them in a House dominated by Margaret Thatcher.

But being Prime Minister isn’t the only way to fill a career with purpose. Robin Cook was over the next few years to become the most feared and admired debater in the Commons. That would have been a career worth having, as a parliamentarian who symbolised the individual holding power to account through the brilliance of his critical mind and razor eloquence. If parliament had such a symbol now, politics might not be held in such low regard. Robin Cook at his finest reached an audience outside the political class, and gave some people a feeling that there was worth in the noise and ritual of the Commons.

While writing Robin Cook: Principles and Power, I looked up and read his response to the Scott Inquiry into arms sales to Iraq in Hansard. Surprisingly, it was as good as I remembered when watching from the press gallery, as he dismantled the government’s defences.

But for about his time as Foreign Secretary, from 1998 to 2001, I didn’t need to rely on hindsight because I had my contemporary notes, written while working as Robin Cook’s press secretary. For example: ‘We acknowledged that Robin was toying with a course of action that could quickly finish him, but we both knew he was right on the edge.’

This was early 1999, when the Foreign Secretary’s promise – and promises – ran painfully into the reality of politics as a series of cock-ups compounded by misjudged responses: another complicated issue which went by the name of the Sandline controversy (arms to Sierra Leone, this time).

Or later that year: ‘When we spoke at 2pm or so on Saturday, he accepted that we were in a hole. He said that if he couldn’t talk Blair round, he didn’t know what he was going to do…. I think it might have to be a resignation issue.’

This one was a problem of arms to Indonesia.

At such moments, it seemed possible that Robin Cook’s career might be ending messily, and would be seen as a failure. But he had the skill and resilience to survive. Writing about that struggle, I have been at the same time re-living life forwards, through my contemporary notes; and understanding life backwards, seeing Robin’s difficulties as smaller than they seemed, because now I know that he came through.

There is a risk in understanding a life backwards of seeing it all as a path taken inevitably towards the known conclusion. Now that we know how high Robin Cook stands as one of the few politicians to resign from Cabinet on principle, there is a temptation to see all his difficulties as early rounds in a wrestling match with his political conscience, inevitably leading to resignation over Iraq in 2003. Some of those struggles were over nothing more than ‘squalid nuisances’ (Sandline) though some (Indonesia) might have been worthy of the principled resignation that – we didn’t know – lay in Robin’s future.

The midnight sun burns out over Spitsbergen in the dramatic cover for Charles Moseley’s Latitude North, due out this autumn. The original image is from a nineteenth century photochrom print entitled “Midnight Sun over Advent Bay, Spitzbergen, Norway”, and it captures the sense of difference and wonder that is part of the charm of the book itself. A couple of final tweaks (notice how we have spelt photochrom with an ‘e’ on the leaf!) and the book is off to the printers next week.